Commercial eCommerce software in PHP

Does anyone have any recommendations or experience with any commercially developed ecommerce/shopping cart software that is better than the open source products (zenCart, oscommerce, etc)? I currently use zenCart and find it very flexible, secure, and functional; however, I am rapidly growing my ecommerce clientelle and if there's something out there that is more robust, more secure, and has more features I'd be willing to purchase it for resale. It would preferably be written (at least mostly) in PHP

I'm not looking for user friendly features, setup, control, etc. Just wondering what the pros use.